<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>菜鸟教程(runoob.com)</title>
    <script src="https://cdn.staticfile.org/jquery/1.10.2/jquery.min.js">
    </script>
    <script>
        $(document).ready(function(){
            $("input").focus(function(){
                $(this).css("background-color","#cccccc");
            });
            $("input").blur(function(){
                $(this).css("background-color","#ffffff");
            });

            $("#test1").click(function () {
                $("#test3").hide(500);
            });

            $("#test2").click(function () {
                $("#test3").show(500);
            });
        });
    </script>
</head>
<body>

Name: <input type="text" name="fullname"><br>
Email: <input type="text" name="email"><br>
<button id="test1">hidden</button><br>
<button id="test2">show</button><br>
<p id="test3">this is a p</p>

</body>
</html>